Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating results:
Total revenues	$ 52,912	$ 44,921	$ 45,087	$ 47,435	$ 49,884	$ 46,274	$ 35,836	$ 27,295	$ 190,355	$ 159,289	$ 55,171
Cost of product revenues	31,814	30,456	25,732	24,843	22,662	20,820	19,014	15,900	112,845	78,396	37,275
Gross profit	21,098	14,465	19,355	22,592	27,222	25,454	16,822	11,395
Other costs and expenses	38,446	35,206	34,827	28,869	22,849	20,675	18,027	18,677
Interest expense and other income (expense), net	(5,612)	3,111	(4,209)	(3,727)	(3,119)	(1,055)	691	(2,334)
Net (loss)	$ (22,960)	$ (17,630)	$ (19,681)	$ (10,004)	$ 1,254	$ 3,724	$ (514)	$ (9,616)	$ (70,275)	$ (5,152)	$ (37,110)
Per share data:
Net income - basic and diluted (in dollars per share)	$ (0.47)	$ (0.39)	$ (3.58)	$ (1.89)					$ (2.68)	$ (1.07)	$ (9.66)
Net income - basic (in dollars per share)						$ 0.04	$ (0.11)	$ (2.09)
Net income - diluted (in dollars per share)						$ 0.03	$ (0.11)	$ (2.09)